JP2000068876A - Communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To design optimum antenna gain and radiation pattern corresponding to the using form of a device by mounting individual demodulation circuits to respective antennas and combining signals after demodulation. SOLUTION: Data 101 are modulated in a modulator 102 and radiated by the antenna 103 for transmission. Radiated electromagnetic waves are received by plural element patch antennas 104-106 and demodulated in demodulators 107-109 installed in the respective element patch antennas 104-106 and the signals are combined in a combiner 110 and outputted as the data 111. A modulation system in this case is amplitude modulation, and by turning it to the amplitude modulation, the demodulator 102 can be constituted of only a diode for detection and a low-pass filter. Thus, at the time of receiving radio waves in the respective element patch antennas 104-106, since they are demodulated immediately after the signals are outputted from the respective element patch antennas, an output signal frequency after the demodulation becomes the same as a modulation signal frequency. Thus, the signals are combined in a common mode at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to high-speed and broadband communication.

[0002]

2. Description of the Related Art In recent years, frequency resources have been depleted due to rapid development of mobile communication. In particular, in the field of data communication, the demand for higher-speed communication that requires a wide frequency resource is increasing due to expansion of applications such as image transmission. In order to alleviate such a problem, exploitation of high frequencies such as millimeter waves has been performed. The millimeter-wave band has a relatively short propagation distance due to the fact that it is not used very much or is absorbed by air, so that a wide frequency resource remains.

In order to improve the performance of a communication system, it is necessary that received signal strength is sufficiently high. To increase the reception strength, it is conceivable to increase the transmission power, increase the antenna gain, or shorten the transmission distance. However, it is generally difficult to easily increase the transmission power from the viewpoints of the performance of the amplifier, interference with other places, power consumption, and the like. The transmission distance cannot be easily changed because the required transmission distance is determined by the application. Therefore, a method of optimizing the radiation pattern of the antenna to improve the gain of the antenna is generally used.

[0004] A technique generally used to improve antenna gain is to use a reflector such as a parabolic antenna, use a dielectric lens, or use a plurality of antenna elements that can be formed on a flat surface such as a printed circuit board. There is a method of combining those signals.

FIG. 7 shows an example of a conventional array antenna.
The hatched portions are element patch antennas, and 701 is one of them. Each element patch antenna is connected in parallel by an impedance converter to output a high-frequency signal 7.
03. 702 indicates one of the impedance converters. In this conventional example, the size 704 of the element patch antenna is １ ／ to の of the wavelength,
The intervals 705 between the element patch antennas are arranged at 0.5 to 1 wavelength. The transmission line is designed such that the difference in the distance from each element patch antenna to the combiner is always an integral multiple of the wavelength so that the signals are combined in phase.

[0006]

However, as shown in FIG. 8, as a cost of improving the antenna gain in either method, the beam width of the antenna is reduced.

In a portable terminal or the like, communication can be easily performed.
It is more convenient to be able to move to some extent such as walking while communicating. However, as described above, when the beam width of the antenna of the portable terminal becomes narrow, the direction of the antenna must be adjusted each time communication is performed, or the beam must be fixed so as not to shift during communication. Therefore, the mobility of the mobile terminal is impaired. Of course, a system for automatically tracking a base station is also conceivable, but a high-speed signal processing and mechanical tracking system is expensive and large and heavy, so it is not preferable to adapt to a portable terminal.

[0008]

A communication system in which a plurality of element antennas are used in a receiving apparatus, individual demodulation circuits are mounted on each of the element antennas, and a demodulated signal is synthesized. Alternatively, a communication system in which a plurality of array antennas are used in a receiving device, individual demodulation circuits are attached to each of the array antennas, and signals after demodulation are combined. Further, the problem is solved by using a communication system in which amplitude modulation or frequency modulation is used as a modulation method in the communication system, and further, by using a communication system in which multiplex modulation is used.

By employing the above-described configuration, the gain can be increased while maintaining the radiation pattern of a wide antenna. Thereby, communication can be performed in a favorable state while maintaining the mobility of the mobile terminal. In addition, since there is no need for regular arrangement of the element antennas, the element antennas can be formed at any place of the mobile terminal, and the element antennas can be easily added in an environment where the gain is insufficient. become able to.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] FIG. 1 is a block diagram of a communication system according to Embodiment 1 of the present invention, and FIG. 2 shows a unit unit of an element patch antenna and a demodulation circuit used in the present embodiment. Show.

In FIG. 1, data 101 is a modulator 10.
2 and is radiated by the transmitting antenna 103. The radiated electromagnetic wave is transmitted to a plurality of element patch antennas 104, 1
.., 109, and demodulated by demodulators 107, 108,..., 109 installed in the respective element patch antennas.
Is output as In this embodiment, the modulation method is amplitude modulation. With the amplitude modulation, the demodulator 102 can be composed of only the detection diode 201 and the low-frequency transmission filter 203 as shown in FIG. 2, and can be realized by a very simple circuit. As shown in FIG. 2, in the receiver, a chip-shaped detection diode 202 and a low-frequency transmission filter 203 inductor are directly mounted on a patch antenna 201 formed on a dielectric substrate (not shown), thereby extremely Small antenna 104-1
06 and the demodulators 107 to 109 are realized.

In a conventional array antenna, in principle, signals from each element patch antenna must be combined in phase. This is because the signals cancel each other when they enter the combiner in opposite phases.

In this embodiment, when a radio wave is received by each of the element patch antennas 104 to 106, the signal is demodulated immediately after a signal is output from each element patch antenna. Therefore, the output signal frequency after demodulation is the same as the modulation signal frequency. become. Generally, the modulation signal frequency is 1/1 compared to the carrier frequency.
00 or less, the wavelength is 100 times or more,
The wavelength is much larger than the size of the entire array antenna. Therefore, even if the element patch antenna is appropriately arranged and the signals are appropriately combined, the signals can always be combined in the same phase.

By integrating the element patch antenna with the demodulation circuit thus formed as shown in FIG.
High received power can be obtained.

In this embodiment, the element patch antennas are arranged relatively regularly as shown in FIG. 3, but they can be arranged completely randomly. Further, even when the antennas are regularly arranged, the antenna intervals can be freely arranged without being bound by the wavelength. Even when the same number of element patch antennas are arranged, in the conventional array antenna, the element patch antennas have to be arranged at intervals of 0.5 to 1 wavelength, but in the present embodiment, the element patch antennas are approaching. If the design is performed in consideration of the mutual coupling (mutual coupling) of the element patch antennas, the interval between the element patch antennas can be reduced to 波長 wavelength or less.

Further, when adding an element patch antenna to an existing system, in the case of a conventional array antenna, the positional relationship between them greatly affects the radiation pattern of the array antenna. However, in the present embodiment, since the radiation pattern of the array antenna is hardly affected by the arrangement of the element patch antennas, it is only necessary to adjust the impedance, and the element patch antenna can be relatively freely added. Can be.

The radiation pattern of the array antenna of this embodiment basically matches the radiation pattern of the element patch antenna. Accordingly, unlike the conventional array antenna, the radiation pattern does not become narrow as the number of element patch antennas increases. However, as the number of element patch antennas in the conventional array antenna increases, the radiation beam width becomes narrower, so the separation gain is improved. The antenna gain in the conventional array antenna is almost proportional to the square of the number of element patch antennas. On the other hand, in the communication system of the present invention, since the radiation beam width is not affected by the number of element patch antennas of the array antenna, the antenna gain is proportional to the number of elements. Therefore, in order to obtain the same antenna gain, a larger number of element patch antennas than in the conventional structure is required. However, as described above, in the present embodiment, the element patch antenna can be freely arranged, and especially in the case of a millimeter wave or the like, the size of the element patch antenna becomes extremely small, so that there is no significant problem.

Second Embodiment A second embodiment of the present invention will be described with reference to FIG. More than the first embodiment,
When it is desired to control the radiation pattern of the antenna, instead of the element patch antenna described in the first embodiment, a plurality of element patch antennas as shown in FIG. By shaping the radiation pattern into a desired radiation beam width and providing a demodulation circuit for each element antenna as shown in FIG. 5, the radiation pattern can be narrowed and the gain can be improved.

FIG. 4 is a diagram showing four element patch antennas constituting the element antenna of the array antenna. 4
The electromagnetic waves received by the three element patch antennas 401 are 3
Through a plurality of impedance converters 402 and through a detection diode 403 and a low-frequency transmission filter 404.
This is output as a modulation signal output 405. These were arrayed in 16 to form an array antenna shown in FIG.

In the present embodiment, the simplest amplitude modulation is used as a modulation method. However, any modulation method can be used as long as demodulation can be performed by an individual antenna, and frequency modulation and phase modulation can be used. In particular, frequency shift keying (FSK) is considered useful because demodulation can be performed relatively easily by combining a plurality of filters.

Third Embodiment A third embodiment of the communication system of the present invention will be described with reference to FIG. As shown in FIG. 6, for example, even when data is already phase-modulated, if the secondary modulation is performed using amplitude modulation or the like to perform multiplex modulation, the receiver can perform the previous amplitude modulation or the like. First demodulation is performed, and the signals from the respective receivers are combined, and then the signals are subjected to secondary demodulation corresponding to the modulation method used first, thereby realizing the configuration as shown in the present invention. Can be. It should be noted that multiplex modulation can be considered not only for secondary but also for tertiary or higher multiplex modulation.

Further, although a planar antenna on a dielectric substrate is used as the antenna, the present invention is not limited to the antenna configuration, and an arbitrary antenna configuration such as a horn antenna or a dielectric lens antenna can be adopted.

[0023]

In the past, since the gain of the antenna and the radiation pattern were always interlocked, it was necessary to use a narrow radiation pattern to obtain the required gain, and especially the ease of use was impaired in portable terminals and the like. . According to the present invention, such restrictions are eliminated, and an optimal antenna gain and radiation pattern can be designed according to the usage of the device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing Embodiment 1 of a communication system of the present invention.

FIG. 2 shows a basic unit of an element patch antenna and a demodulation circuit according to the first embodiment of the present invention.

FIG. 3 is an array antenna according to the first embodiment of the present invention.

FIG. 4 shows an element antenna according to a second embodiment of the present invention.

FIG. 5 is an array antenna according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a third embodiment using multiplex modulation in the communication system of the present invention.

FIG. 7 shows a configuration of a conventional array antenna.

FIG. 8 shows a relationship between a conventional array antenna gain and a radiation beam width.

[Explanation of symbols]

 101 Data 102 Modulator 103 Element Patch Antenna 104 Element Patch Antenna 105 Element Patch Antenna 106 Element Patch Antenna 107 Demodulator 108 Demodulator 109 Demodulator 110 Combiner 111 Data 201 Element Patch Antenna 202 Detecting Diode 203 Low Frequency Transmission Filter 204 Modulation Signal output 301 Modulated signal output 401 Element patch antenna 402 Impedance converter 403 Detection diode 404 Low frequency transmission filter 405 Modulated signal output 501 Modulated signal output 601 Data 602 Primary modulation 603 Secondary modulation 604 Element patch antenna 605 Element patch antenna 606 Element patch antenna 607 Element patch antenna 608 Primary demodulation 609 Primary demodulation 610 Primary demodulation 611 Combiner 612 Secondary demodulation 623 Data 701 Element patch antenna 702 Impedance converter 703 High frequency signal output 704 Element patch antenna size 705 Element patch antenna spacing

Claims (5)

[Claims] 1. A receiving apparatus comprising: a plurality of antennas;
A communication system comprising: attaching an individual demodulation circuit to each antenna; and synthesizing a demodulated signal. 2. The communication system according to claim 1, wherein said antenna is an array antenna. 3. The communication system according to claim 1, wherein amplitude modulation is used as a modulation method. 4. The communication system according to claim 1, wherein frequency modulation is used as a modulation method. 5. The communication system according to claim 1, wherein a multiplex modulation is used as a modulation method.